JP5297092B2 - Composition for fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the following problems: a catalyst layer using a composition for a fuel cell is easily cracked, and methanol solubility resistance of the catalyst layer is low. <P>SOLUTION: The composition for the fuel cell contains a polymer compound in which a proton conductive group is introduced into a polymer compound having an aromatic unit, a compound X having two or more of a group represented by general formula (1)-CH<SB>2</SB>OR (in the formula, R represents hydrogen, an alkyl group, or an acyl group.), and a solvent. The boiling point of the solvent is 100-300&deg;C, and acid is contained. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a polymer electrolyte fuel cell composition.

Solid polymer fuel cells are expected as one of the pillars of new energy technology. Solid polymer fuel cells that use polymer electrolytes with proton-conducting substituents can be operated at low temperatures and can be reduced in size, weight, mobile vehicles such as automobiles, household cogeneration systems, and civilian use. Application to small portable devices is under consideration. In particular, direct methanol fuel cells that use methanol directly as fuel have a simple structure, ease of fuel supply and maintenance, and / or characteristics such as high energy density. As such, it is expected to be applied to small portable devices for private use such as mobile phones and notebook computers.

In the direct methanol fuel cell, a polymer electrolyte having excellent methanol solubility resistance represented by Patent Document 1 is used. However, when a catalyst layer is produced using a fuel cell composition represented by Patent Document 1, the catalyst layer is cracked because a solvent having a boiling point of less than 100 ° C. is used, and production of the catalyst layer is performed. There was a problem that it was difficult. Furthermore, when the cracked catalyst layer is directly used for a methanol fuel cell, there is a problem that power generation characteristics are remarkably deteriorated. In order to solve the above problems, techniques represented by Patent Documents 2 and 3, that is, a technique for suppressing cracking of the catalyst layer using a higher alcohol or a non-alcohol organic solvent as a solvent are applied. There was a problem that the reaction between the molecular electrolyte and the compound X did not proceed, and the methanol solubility resistance of the catalyst layer was significantly lowered.
JP2008-4279 JP 2006-253042 A JP 2003-208903 A

  In direct methanol fuel cells, a catalyst layer is an essential component, and it is strongly desired to produce a catalyst layer that does not crack or has enough cracking to withstand practical use, and has excellent methanol solubility resistance. ing.

  The present invention has been made in view of the above-mentioned problems, and the object of the present invention is a catalyst for direct methanol fuel cell which is not cracked or has few cracks to the extent that it can withstand practical use and has excellent methanol solubility resistance. Is to provide a layer.

As a result of intensive studies to solve the above problems, the present inventor has at least a polymer compound in which a proton conductive group is introduced into a polymer compound having an aromatic unit, represented by the following general formula (1). A solvent having a boiling point of 100 ° C. or more and 300 ° C. or less for a fuel cell composition containing at least one compound X having two or more groups and a solvent, and with respect to 100 parts by weight of the solvent In addition, it has been found that by including 1 part by weight or more and 10 parts by weight or less of an acid, a catalyst layer that does not crack or has sufficient cracking resistance to withstand practical use and that has excellent methanol solubility resistance can be produced. The present invention has been completed. The present invention has been completed based on such novel findings, and includes the following inventions.
-CH ₂ OR ··· (1)
(In the formula, R represents hydrogen, an alkyl group, or an acyl group, and R contained in one type of compound is the same and may be the same or different from each other.) In the general formula (1), R preferably represents hydrogen, an alkyl group having 1 to 20 carbon atoms, or an acyl group having 1 to 20 carbon atoms.

  That is, the solvent used in the fuel cell composition according to the present invention may be N, N-dimethylformamide, dimethyl sulfoxide, or N-methylpyrrolidone.

  The acid used in the fuel cell composition according to the present invention may be methanesulfonic acid.

  The proton conductive group in the polymer compound having an aromatic unit used in the present invention may be a sulfonic acid group.

  The ion exchange capacity of the polymer compound in which a proton conductive group is introduced into the polymer compound having an aromatic unit may be 0.9 meq / g or more and 6 meq / g or less.

  The polymer compound having an aromatic unit may be an aromatic polyether polymer.

Moreover, the following structural formula may be sufficient as the at least 1 or more types of compound X which has 2 or more groups shown by following General formula (1).
-CH ₂ OR ··· (1)

また、前記燃料電池に用いられる燃料電池用触媒層形成材料は、前記燃料電池用組成物および燃料電池用触媒を含んでもよい。

The fuel cell catalyst layer forming material used in the fuel cell may include the fuel cell composition and the fuel cell catalyst.

The method for producing a fuel cell catalyst layer containing the fuel cell catalyst layer forming material may include at least the following steps (I), (II), (III) and / or (IV).
(I) a step of applying a fuel cell catalyst layer forming material containing at least the fuel cell composition and the fuel cell catalyst on a substrate;
(II) removing the solvent from the catalyst layer forming material,
(III) a step of chemically reacting the polymer electrolyte and the compound X contained in the fuel cell composition to obtain a reaction product;
(IV) A step of removing acid from the catalyst layer.

  The step (III) may be heating at a temperature not lower than the temperature at which the chemical reaction proceeds and not higher than 300 ° C.

  The substrate may be a polymer sheet, an inorganic sheet, or a conductive porous sheet.

  The step of removing the acid from the catalyst layer may be bringing the catalyst layer into contact with water.

  Further, the fuel cell catalyst layer or the fuel cell gas diffusion electrode produced by the production method may be used for a fuel cell membrane electrode assembly, or the fuel cell membrane electrode assembly may be a fuel cell. May be used.

According to the present invention, at least one polymer compound in which a proton conductive group is introduced into a polymer compound having an aromatic unit, at least one group having two or more groups represented by the general formula (1). Use of a solvent having a boiling point of 100 ° C. or more and 300 ° C. or less for the composition for a fuel cell containing Compound X and a solvent, and 1 part by weight or more and 10 parts by weight or less with respect to 100 parts by weight of the solvent By including an acid, it is possible to produce a catalyst layer that does not crack or has few cracks to the extent that it can be practically used, and has excellent methanol solubility resistance.
Therefore, the direct methanol fuel cell provided with the catalyst layer using the fuel cell composition of the present invention showed excellent power generation characteristics.

  An embodiment of the present invention will be described as follows. Note that the present invention is not limited to the following description.

  The fuel cell composition of the present invention will be specifically described.

The composition for a fuel cell used in the present invention has at least two groups represented by the following general formula (1), a polymer compound in which a proton conductive group is introduced into a polymer compound having an aromatic unit. A fuel cell composition comprising at least one compound X and a solvent, wherein the solvent has a boiling point of 100 ° C. or higher and 300 ° C. or lower, and 1 part by weight with respect to 100 parts by weight of the solvent. It is preferable that 10 parts by weight or less of acid is contained. Details of each component will be described later.
-CH ₂ OR ··· (1)
(In the formula, R represents hydrogen, an alkyl group, or an acyl group, and R contained in one compound is the same and may be the same or different.)
Any method can be applied as a method for obtaining a composition for a fuel cell comprising a polymer compound obtained by introducing a proton conductive group into the polymer compound having at least the aromatic unit of the present invention and the compound X. . For example, a method of directly mixing a polymer compound in which a proton conductive group is introduced into the polymer compound having an aromatic unit and the compound X, a proton conductive group in the polymer compound having an aromatic unit A method of immersing and impregnating the introduced polymer compound in a solution containing the compound X, a polymer compound in which a proton conductive group is introduced into the polymer compound having the aromatic unit, and the compound X Examples of the method include mixing as a solution or dispersion. In view of ease of handling, a method of mixing as a solution or a dispersion is preferred.

  In the fuel cell composition of the present invention, the solid content of the polymer compound in which a proton conductive group is introduced into the polymer compound having an aromatic unit and the compound X is 1 wt% or more and 50 wt% or less. It is preferable that If the amount is less than 1 wt%, the viscosity is too small, which may make it difficult to produce a catalyst layer described later. If the viscosity is higher than 50 wt%, the viscosity is too large, making the later described catalyst layer difficult to manufacture. There is a fear.

  The polymer compound in which a proton conductive group is introduced into at least the polymer compound having an aromatic unit used in the present invention will be specifically described.

  The polymer compound in which the proton conductive group is introduced into at least the polymer compound having an aromatic unit used in the present invention may be any compound that can introduce a proton conductive group into the aromatic unit in the polymer compound. There is no particular limitation, for example, polyether ketone, polyether ether ketone, polyether ketone ketone, polyether ether ketone ketone, polysulfone, polyether sulfone, polyether ether sulfone, polyaryl ether sulfone, poly 1,4-biphenylene ether Ether sulfone, polyarylene ether sulfone, polyparaphenylene, polyphenylene ether, modified polyphenylene ether, polyphenylene sulfoxide, polyphenylene sulfone, polyphenylene sulfide, polyphenylene sulfide sulfone , Polystyrene, syndiotactic polystyrene, polyethylene-graft-polystyrene copolymer, styrene- (ethylene-propylene) -styrene block copolymer, styrene- (ethylene-butylene) -styrene block copolymer, styrene-isobutylene-styrene Examples thereof include block copolymers, polyimides, polyetherimides, polybenzimidazoles, polybenzoxazoles, polybenzothiazoles, cyanate ester resins, and derivatives thereof. These polymer compounds may be one kind or plural. Among these, in view of availability and reactivity with the compound X, aromatic polyethers such as polyether ketone, polyether ether ketone, polysulfone, polyether sulfone, polyphenylene ether, and modified polyphenylene ether are used. Molecular compounds are preferred, and polyether ether ketone is particularly preferred.

  As a method for obtaining a polymer compound in which a proton conductive group is introduced into a polymer compound having an aromatic unit of the present invention, a monomer having a proton conductive group and a monomer having no proton conductive group are copolymerized. Known methods such as a method of introducing a proton conductive group by a polymer reaction with a polymer compound having an aromatic unit, and the like can be applied. Examples of the former include, for example, a method in which a monomer having a proton conductive group into which an appropriate protective group is introduced as necessary and a monomer having no proton conductive group are copolymerized and then deprotected. . Examples of the latter include a method of reacting a polymer compound having an aromatic unit with a sulfonating agent such as chlorosulfonic acid in a solvent, a method of reacting in concentrated sulfuric acid or fuming sulfuric acid, and the like. .

  The proton conductive group of the present invention is not particularly limited as long as it can dissociate protons in a water-containing state, and examples thereof include sulfonic acid groups, phosphoric acid groups, phosphonic acid groups, carboxyl groups, and phenolic hydroxyl groups. These may be used alone or in combination. Among these, a sulfonic acid group is particularly preferable in view of ease of introduction of a proton conductive group and proton conductivity of the resulting polymer compound.

  The ion exchange capacity of the polymer compound in which a proton conductive group is introduced into the polymer compound having an aromatic unit of the present invention is preferably 0.9 meq / g or more and 6 meq / g or less. If it is less than 0.9 meq / g, the proton conductivity required for power generation of the fuel cell may not be obtained, and if it is more than 6 meq / g, the polymer compound is used in the reaction for having the ion exchange capacity. There is a risk of disassembly.

  In the compound X of the present invention, the presence of two or more of the functional groups in one molecule makes it possible for the polymer X to be “a polymer in which a proton conductive group is introduced into a polymer compound having an aromatic unit”. Since "compound" can be bonded between molecules, it becomes possible to improve the heat resistance of the reaction product obtained and to suppress swelling / solubility and permeability to hydrogen-containing liquids such as methanol. . The compound X is not particularly limited as long as two or more of the functional groups are present in one molecule. However, the compound X has a proton conductive group introduced into the polymer compound having an aromatic unit. Reactivity with the polymer compound, heat resistance of the reaction product with the polymer compound having a proton conductive group introduced into the polymer compound having an aromatic unit, and against hydrogen-containing liquids such as methanol. Considering the effect of suppressing swelling / solubility and permeability, an aromatic compound is preferable. This compound may be a hydrocarbon aromatic compound having a benzene ring, a naphthalene ring or the like, or a heteroaromatic compound having an element other than carbon such as a triazine ring.

  Further, R of the functional group present in two or more molecules in the compound X1 is not particularly limited as long as it is any one of hydrogen, an alkyl group, and an acyl group, and the Rs of the functional groups are independent and the same. It may or may not be. Considering the availability of the compound and the ease of removal of the compound by-produced by the reaction with the above-mentioned “polymer compound in which a proton conductive group is introduced into the polymer compound having an aromatic unit”, hydrogen, A methyl group or an acetyl group is preferred. When used in a direct methanol fuel cell, it is particularly preferable that the functional group R is hydrogen or a methyl group because only water or methanol contained in the fuel cell is by-produced.

  Such compound X includes, for example, 1,2-bis (hydroxymethyl) benzene, 1,3-bis (hydroxymethyl) benzene, 1,4-bis (hydroxymethyl) benzene, 2,6-bis (hydroxy). Methyl) phenol, 3,5-bis (hydroxymethyl) phenol, 4,6-bis (hydroxymethyl) -o-cresol, 2,6-bis (hydroxymethyl) -p-cresol, 2,6-bis (hydroxy) Methyl) -4-t-butylphenol, 2,2′-bis (hydroxymethyl) diphenyl ether, 4,4′-bis (hydroxymethyl) diphenyl ether, 1,2,4-benzenetrimethanol, 1,3,5-benzene Trimethanol, 4,4′-methylenebis [2,6-di (hydroxymethyl)] phenol, oxybis 3,4-dihydroxymethyl) benzene, 1,2-bis (methoxymethyl) benzene, 1,3-bis (methoxymethyl) benzene, 1,4-bis (methoxymethyl) benzene, 2,6-bis (methoxymethyl) ) -P-cresol, 2,6-bis (methoxymethyl) -4-tert-butylphenol, 2,4,6-tris [bis (methoxymethyl) amino] -1,3,5-triazine, Cymel (registered trademark) , Manufactured by Nippon Cytec Industries Co., Ltd.), DML-PC (produced by Honshu Chemical Industry Co., Ltd.), TML-BPA-MF (produced by Honshu Chemical Industry Co., Ltd.), TML-BPAF-MF (produced by Honshu Chemical Industry Co., Ltd.), DML -OC (made by Honshu Chemical Industry Co., Ltd.), DImethoxymethyl p-CR (made by Honshu Chemical Industry Co., Ltd.), DML-MBPC (Honshu Chemical Industry Co., Ltd.), DML-BPC (Honshu Chemical Industry Co., Ltd.), TML-BP (Honshu Chemical Industry Co., Ltd.), TMOM-BP (Honshu Chemical Industry Co., Ltd.), DML-PEP (Honshu) Chemical Industry Co., Ltd.), DML-34X (Honshu Chemical Industry Co., Ltd.), DML-PSBP (Honshu Chemical Industry Co., Ltd.), DML-PTBP (Honshu Chemical Industry Co., Ltd.), DML-PCHP (Honshu Chemical Industry Co., Ltd.) Co., Ltd.), DML-POP (Honshu Chemical Industry Co., Ltd.), DML-PFP (Honshu Chemical Industry Co., Ltd.), DML-MBOC (Honshu Chemical Industry Co., Ltd.), HML-TPPHBA (Honshu Chemical Industry Co., Ltd.) ), HMOM-TPPHBA (manufactured by Honshu Chemical Industry Co., Ltd.), 26DMPC (manufactured by Asahi Organic Materials Co., Ltd.), 46DMOC (Asahi Organic Material Industries Co., Ltd.) ), DM-BIPC-F (Asahi Organic Materials Industries Co., Ltd.), DM-BIOC-F (Asahi Organic Materials Industries Co., Ltd.), TM-BIP-A (Asahi Organic Materials Industries Co., Ltd.), Nicarak ( (Manufactured by Sanwa Chemical Co., Ltd.) and the like, but are not limited thereto. Furthermore, although partially overlapping with the above, compound X can also be exemplified by compounds represented by the following chemical formula. That is, 10 types of the following structural formulas (2)-(11), 15 types of (12)-(26), 15 types of (27)-(41), and 4 types of (42)-(45) Although a compound can be illustrated, it is not limited only to these.

これらの化合物は１種類であっても複数であってもかまわない。これらのなかで、入手の容易さや前記「芳香族単位を有する高分子化合物にプロトン伝導性基が導入されてなる高分子化合物」との反応性、前記「芳香族単位を有する高分子化合物にプロトン伝導性基が導入されてなる高分子化合物」との反応生成物の耐熱性やメタノールなどの水素含有液体に対する膨潤性・溶解性や透過性の抑制効果などを考慮すると、下記構造式（２）―（１１）で示される１０種類の化合物

These compounds may be one kind or plural. Among them, availability and reactivity with the above-mentioned “polymer compound in which a proton-conducting group is introduced into a polymer compound having an aromatic unit” and the above-mentioned “polymer compound having an aromatic unit as a proton Considering the heat resistance of the reaction product with the polymer compound with the introduction of a conductive group and the effect of suppressing swelling, solubility and permeability of hydrogen-containing liquids such as methanol, the following structural formula (2) -10 kinds of compounds represented by (11)

からなる群から選択される少なくとも１種以上であることが特に好ましい。

Particularly preferred is at least one selected from the group consisting of

  In the composition for a fuel cell of the present invention, the compounding ratio of the “polymer compound in which a proton-conducting group is introduced into the polymer compound having an aromatic unit” and the compound X is the above-mentioned “aromatic unit. The compound X is preferably 1 to 50 parts by weight, more preferably 5 to 40 parts by weight based on 100 parts by weight of the polymer compound obtained by introducing a proton conductive group into the polymer compound. When the compound X is less than 1 part by weight, the effect of improving the heat resistance of the reaction product with the “polymer compound in which a proton conductive group is introduced into the polymer compound having an aromatic unit”, methanol, etc. There is a risk that the effect of suppressing the swellability / solubility and permeability to hydrogen-containing liquid will be reduced. On the other hand, when the compound X exceeds 50 parts by weight, the proton conductivity and mechanical strength of the reaction product with the “polymer compound in which a proton conductive group is introduced into the polymer compound having an aromatic unit” are increased. May fall.

  The solvent used in the fuel cell composition of the present invention can dissolve or disperse the above-mentioned “polymer compound in which a proton conductive group is introduced into a polymer compound having an aromatic unit” and the compound X, and the boiling point. Is preferably 100 ° C. or higher and 300 ° C. or lower, for example, N, N-dimethylformamide, N-methylpyrrolidone. Or a dimethyl sulfoxide etc. can be illustrated. If the boiling point is less than 100 ° C., cracking of the catalyst layer may occur when a catalyst layer described later is produced. Moreover, when higher than 300 degreeC, there exists a possibility that a polymer electrolyte may decompose | disassemble in the below-mentioned solvent removal. Moreover, it is preferable that the boiling point of a solvent is less than the decomposition temperature of a polymer electrolyte. The decomposition temperature of the polyelectrolyte can be determined by a value measured by thermal analysis typified by TGA, for example, a temperature of weight reduction that appears after weight loss due to water contained in the polymer electrolyte. In addition, when the solvent used is water-soluble, the solubility and dispersibility of the “polymer compound in which a proton conductive group is introduced into the polymer compound having an aromatic unit” and the compound X are impaired. It does not matter if it contains water to the extent that it does not.

  The acid contained in the fuel cell composition of the present invention is not particularly limited as long as it promotes the chemical reaction between the polymer electrolyte and the compound X. For example, methanesulfonic acid, sulfuric acid, or A chlorosulfonic acid etc. can be illustrated. In particular, it is preferable to use methanesulfonic acid which does not cause significant modification of the solvent.

  Further, the acid is preferably contained in an amount of 1 part by weight or more and 10 parts by weight or less with respect to 100 parts by weight of the solvent. If the amount is less than 1 part by weight, the chemical reaction between the polymer electrolyte and the compound X may not proceed. If the amount exceeds 10 parts by weight, the fuel cell catalyst used later may be deteriorated.

  The fuel cell catalyst layer forming material of the present invention will be specifically described.

  The fuel cell catalyst layer forming material of the present invention is a mixture containing at least the fuel cell composition and the fuel cell catalyst. The fuel cell catalyst layer forming material may contain a binder or a dispersant.

  The form of the binder and the dispersant is not particularly limited, but in consideration of ease of handling, a solution or dispersion dissolved or dispersed in an arbitrary solvent is preferable. The concentration is preferably 1 to 90 wt%, more preferably 1 wt% to 75 wt%, and particularly preferably 1 wt% to 50 wt%. When the concentration is less than 1 wt%, the formation of the catalyst layer is difficult because the viscosity of the catalyst layer forming material is small. When the concentration is greater than 90 wt%, the formation of the catalyst layer is difficult because the viscosity of the catalyst layer forming material is large. May be difficult.

  The catalyst for the fuel cell is not particularly limited, and a catalyst active for the electrode reaction of the fuel cell can be used. On the cathode side, a noble metal such as platinum is added to a high surface area conductive material such as a catalyst capable of reducing an oxidizing agent (oxygen, air, etc.), such as carbon black, ketjen black, activated carbon, carbon nanohorn, and carbon nanotube. Examples include supported ones and noble metals such as platinum black. Furthermore, a composite or alloy catalyst made of platinum and an arbitrary catalyst metal can be used for improving the reduction ability, stabilizing the catalyst metal, or extending the life. Further, the component may be three or more components using iron, tin, rare earth elements and the like. On the anode side, a noble metal such as platinum is supported on a high surface area conductive material such as carbon black, ketjen black, activated carbon, carbon nanohorn, or carbon nanotube, which has the ability to oxidize fuel (methanol, hydrogen, etc.). Or a precious metal such as platinum black. Furthermore, in order to suppress catalyst poisoning by carbon monoxide, aldehydes, carboxylic acids, etc., which are by-products during fuel oxidation, a composite or alloy catalyst made of platinum and ruthenium can be used instead of platinum. Further, the component may be three or more components using iron, tin, rare earth elements, etc. for stabilization and long life.

  The manufacturing method of the catalyst layer for fuel cells of this invention is demonstrated concretely.

The method for producing a fuel cell catalyst layer containing the fuel cell catalyst layer forming material of the present invention is a production method comprising at least the following steps (I), (II), (III) and / or (IV): is there.
(I) a step of applying a fuel cell catalyst layer forming material containing at least the polymer electrolyte, the compound X, and the fuel cell catalyst on a substrate;
(II) removing the solvent from the catalyst layer forming material,
(III) a step of chemically reacting the polymer electrolyte and the compound X to obtain a reaction product;
(IV) A step of removing acid from the catalyst layer.

  In the method for producing a fuel cell catalyst layer according to the present invention, (I) "a step of applying a catalyst layer forming material containing at least the polymer electrolyte, the compound X, and the fuel cell catalyst onto a substrate. Will be specifically described.

  The catalyst layer forming material used in the present invention may contain additives such as a non-electrolyte binder, a water repellent, a dispersant, a thickener, and a pore-forming agent as necessary. In addition, those additives conventionally known to those skilled in the art can be used, and other specific configurations are not particularly limited.

  As a method for applying the catalyst layer forming material to the base material, the following application methods can be used depending on the viscosity and the type of the base material. The method for applying the catalyst layer forming material onto the base material may be any conventionally known application method for those skilled in the art, and other specific configurations are not particularly limited. For example, methods using a knife coater, a bar coater, a spray, a dip coater, a spin coater, a roll coater, a die coater, a curtain coater, screen printing, and the like can be listed, but are not limited to the present invention.

  In the present invention, when a polymer sheet and an inorganic sheet are used as a base material, a fuel cell catalyst layer transfer sheet is used, and when a conductive porous sheet is used, a fuel cell gas diffusion electrode is used. Can be manufactured.

  The polymer sheet used in the method for producing a fuel cell catalyst layer transfer sheet of the present invention is literally a polymer film conventionally known to those skilled in the art, and other specific configurations are not particularly limited. Such polymer sheets include polyimide, polyethylene terephthalate, polyparvanic acid aramid, polyamide (nylon), polysulfone, polyethersulfone, polyphenylene sulfide, polyetheretherketone, polyetherimide, polyarylate, polyethylene naphthalate, ethylenetetrafluoro. Selected from the group consisting of ethylene copolymer (ETFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroperfluoroalkyl vinyl ether copolymer (PFA), and polytetrafluoroethylene (PTFE). Including at least one kind is preferable because it can withstand the heating conditions in the production process and is easily available industrially.

  The inorganic sheet used in the method for producing a catalyst layer transfer sheet for a fuel cell according to the present invention may literally be an inorganic sheet conventionally known to those skilled in the art, and the other specific configurations are not particularly limited. The inorganic sheet preferably contains at least one selected from the group consisting of titanium, stainless steel, aluminum, and copper because it can withstand the heating conditions in the manufacturing process and is easily available industrially.

  The conductive porous sheet used in the method for producing a gas diffusion electrode for a fuel cell of the present invention may literally be a conductive porous sheet conventionally known to those skilled in the art, and other specific configurations are particularly limited. Not. In the method for producing an electrode for a fuel cell of the present invention, the conductive porous sheet includes carbon paper, carbon cloth, and the like, because of the diffusibility of fuel and oxidant, electrochemical stability, industrial availability, and the like. It is preferably at least one selected from the group consisting of carbon felt. In addition, the conductive porous sheet is preferably subjected to water repellent treatment from the viewpoint of suppressing flooding due to humidified water containing fuel or oxidant, liquid fuel or generated water. The conductive porous sheet is coated with the fuel cell catalyst layer forming material from the viewpoint that electrical contact between the catalyst layer and the conductive porous sheet can be improved and moisture management can be appropriately performed. It is preferable to provide a layer made of a water repellent conductive material on the surface. That is, the layer made of the water repellent conductive material is placed between the catalyst layer and the conductive porous sheet. Examples of the water repellent conductive material include conductive fine particles such as carbon black and a fluorine-based polymer compound such as tetrafluoroethylene (PTFE), but the present invention is not limited thereto. .

  The (II) “step of removing the solvent from the catalyst layer forming material” in the method for producing a fuel cell catalyst layer of the present invention will be specifically described.

  The method for removing the solvent from the catalyst layer forming material is preferably heating by a normal oven or the like, or heating by a vacuum oven. In the case of heating with an oven, it is preferable that the inside of the oven is filled with an inert gas such as nitrogen because combustion of the catalyst layer can be prevented. The heating temperature is preferably not less than the boiling point of the solvent and less than the decomposition temperature of the polymer electrolyte, that is, not less than 100 ° C. and not more than 300 ° C. If the temperature is lower than 100 ° C, the solvent may not be removed. If the temperature is higher than 300 ° C, the polymer electrolyte may be decomposed when the solvent is removed. Further, this heating may also serve as a “step of obtaining a reaction product by chemically reacting the polymer electrolyte and the compound X” described later.

  In the method for producing a fuel cell catalyst layer and a fuel cell electrode of the present invention, (III) “Step of obtaining a reaction product by chemically reacting the polymer electrolyte and the compound X” will be specifically described. To do.

  In the present invention, the reaction product of the polymer electrolyte and the compound X can be obtained by heating the mixture. In addition, this chemical reaction can occur sufficiently in air as long as it is heated. The heating temperature usually needs to be in the range of the temperature at which the chemical reaction proceeds to the decomposition temperature of the polymer electrolyte and the boiling point and decomposition temperature of the compound X. In order to obtain a fuel cell catalyst layer and a fuel cell electrode in which these chemical reactions proceed rapidly and can exhibit excellent performance, heating is performed at a temperature not lower than the temperature at which the chemical reaction proceeds and not higher than 300 ° C. Is preferred. Here, the temperature at which the chemical reaction proceeds can be confirmed by a change in the amount of heat generated before and after the reaction by a differential scanning calorimeter (DSC) or a change in mechanical characteristics by a thermomechanical analyzer (TMA) or the like. . When the heating temperature is lower than the above temperature range, the reaction may not occur, the reaction may be insufficient, or the reaction time may be prolonged. On the other hand, when the heating temperature is higher than the above temperature range, there is a risk that side reactions or decomposition reactions that cause performance degradation may occur, or proton conductive groups of the polymer electrolyte may be decomposed and eliminated. The heating conditions are preferably 130 ° C. or higher and 200 ° C. or lower, and the time is 1 minute or longer and 180 minutes or shorter, preferably 5 minutes or longer and 60 minutes or shorter. By selecting such heating conditions, the production method is excellent in terms of both characteristics and productivity. In the present invention, the heating method at the time of the chemical reaction is not particularly limited, and examples thereof include heating by a normal oven, heating by a vacuum oven, heating by a press machine, and the like, but are not limited thereto. Moreover, you may heat at the time of the heating press-contact at the time of the membrane electrode assembly for fuel cells mentioned later.

  (IV) “Step of removing acid from catalyst layer” in the method for producing a fuel cell catalyst layer and a fuel cell electrode of the present invention will be specifically described.

  The step of removing the acid of the present invention is not particularly limited. For example, the transfer sheet, the gas diffusion electrode, and the membrane electrode assembly are immersed in a solvent such as water or alcohol, or the membrane electrode assembly is used as a fuel cell. After incorporation into the acid, the acid may be removed by flowing a solvent through the anode and cathode of the fuel cell. As the solvent used for removing the acid, water is particularly preferably used because it does not dissolve the polymer electrolyte contained in the catalyst layer.

  The membrane electrode assembly for a fuel cell of the present invention will be specifically described.

  In the membrane electrode assembly for a fuel cell according to the present invention, a fuel cell catalyst layer, a fuel cell catalyst layer transfer sheet, and a fuel cell gas diffusion electrode are disposed on at least one surface of the polymer electrolyte membrane, and are heated and pressed. There are no particular limitations on the specific configuration such as other manufacturing conditions, components, materials, and blending ratios.

  The polymer electrolyte membrane used for the fuel cell membrane electrode assembly of the present invention may be literally a polymer electrolyte membrane conventionally known to those skilled in the art, and other specific configurations are not particularly limited. Examples of perfluorocarbon sulfonic acid polymer electrolyte membranes include Nafion manufactured by DuPont, Flemion manufactured by Asahi Glass Co., Ltd., Aciplex manufactured by Asahi Kasei Co., Ltd., and Gore Select manufactured by Gore. As the non-fluorine polymer electrolyte membrane, those conventionally known to those skilled in the art can be used. For example, as a polymer electrolyte membrane suitable for a membrane / electrode assembly for a direct methanol fuel cell or a polymer electrolyte used in the present invention, a non-electrolyte porous support was filled with the polymer electrolyte. It is preferable to use a pore filling membrane or a composite electrolyte membrane in which a polymer electrolyte and a non-electrolyte are combined.

  In the production of the fuel cell membrane / electrode assembly of the present invention, the conditions of the heat-pressure welding may literally be those conventionally known to those skilled in the art, and the other specific configurations are not particularly limited. The optimum conditions need to be set as appropriate according to the type of polymer electrolyte contained in each of the electrolyte membrane, the anode side catalyst layer, and the cathode side catalyst layer. Generally, the temperature of the heating and pressure welding is equal to or lower than the thermal deterioration or thermal decomposition temperature of the polymer electrolyte contained in the polymer electrolyte membrane or the catalyst layer, and the polymer electrolyte contained in the polymer electrolyte membrane or the catalyst layer. It is preferable to carry out the reaction at a temperature above the glass transition point or softening point of the polymer electrolyte, or at a temperature above the glass transition point or softening point of the polymer electrolyte contained in the polymer electrolyte membrane or the catalyst layer. In addition, the pressurizing condition of the heat pressure contact is generally in the range of 0.1 MPa or more and 20 MPa or less, and the polymer electrolyte membrane and the catalyst layer are in sufficient contact with each other, and there is no deterioration in characteristics due to significant deformation of the material used. preferable. Further, in the heating and pressure welding, the above-mentioned “step of chemically reacting the polymer electrolyte and the compound X to obtain a reaction product” may also be used.

  In the membrane / electrode assembly of the present invention, the catalyst layer obtained by the production method of the present invention is disposed on both surfaces of the polymer electrolyte membrane, the polymer electrolyte membrane and the catalyst layer are joined, and then the polymer film is bonded. By peeling, a three-layer membrane electrode assembly (three-layer MEA: Membrane Electrode Assembly, CCM: Catalyst CoatIng Membrane) comprising a polymer electrolyte membrane, an anode-side catalyst layer, and a cathode-side catalyst layer can be produced.

  In addition, when a gas diffusion electrode for a fuel cell obtained by the production method of the present invention is used instead of the catalyst layer, a five-layer membrane electrode assembly in which a diffusion layer is formed outside the three-layer membrane electrode assembly (5-layer MEA) can be manufactured.

  Furthermore, at least a layer made of a water repellent conductive material composed of conductive carbon particles and a water repellent agent is provided between the diffusion layer and the catalyst layer as needed, and the electrolyte at the periphery of the diffusion layer It is added that a seven-layer membrane electrode assembly formed by arranging a pair of gaskets on the membrane is also within the scope of the present invention.

The fuel cell of the present invention will be specifically described.
In the fuel cell of the present invention, the membrane electrode assembly of the present invention is inserted between a pair of separators in which a flow path for feeding fuel and an oxidant is formed. A fuel cell containing is obtained. The separator is not particularly limited, and for example, a conductive material such as carbon graphite or stainless steel can be used. In particular, when a metal material such as stainless steel is used, it is preferable to perform a corrosion resistance treatment.

  In the fuel cell of the present invention, a liquid such as methanol can be used for the anode, although it is not particularly limited, and oxygen or air can be used for the cathode as an oxidant, although not particularly limited. The oxidant supplied to the cathode may be humidified with water, but the use of a non-humidified oxidant is preferable because the cathode flooding phenomenon can be suppressed.

  It should be noted that the polymer electrolyte fuel cells according to the present embodiment can be used alone or in a stacked manner to form a stack, or a fuel cell system incorporating them.

  Furthermore, it should be noted that the polymer electrolyte fuel cell using hydrogen as a fuel is also within the scope of the present invention.

  Hereinafter, examples will be shown, and the embodiment of the present invention will be described in more detail. Of course, the present invention is not limited to the following examples, and it goes without saying that various aspects are possible in detail. Further, the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope shown in the claims, and the present invention is also applied to the embodiments obtained by appropriately combining the disclosed technical means. It is included in the technical scope of the invention.

EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited at all by these Examples, In the range which does not change the summary, it can change suitably.
Example 1
<Synthesis of compound used as "polymer compound in which proton conductive group is introduced into polymer compound having aromatic unit": Synthesis of sulfonic acid group-containing polyether ether ketone (hereinafter, S-PEEK)>
First, 552.0 g of sulfuric acid was put in a reaction vessel equipped with a mechanical stirrer, a reflux pipe, and a calcium chloride pipe, and then 22.2 g of PEEK450PF (polyether ether ketone manufactured by Victorex MC) was added with stirring, and the mixture was brought to room temperature. And stirred for 3 days. The reaction solution was dropped into ion-exchanged water to precipitate a reaction product, followed by filtration, and washed with ion-exchanged water until the filtrate became neutral. The obtained reaction product was dried at 105 ° C. for 8 hours under vacuum to obtain 26.94 g of a yellow solid. The obtained solid had an IEC of 2.2 meq / g and a proton conductivity of 6.0 × 10 ⁻² S / cm.

  As compound X, B-5: “5,5 ′-[2,2,2-TrIfluoro-1- (trIfluoromethyl) ethylIdene] bIs [2-hydroxy-1,3-benzeneImethanol]” (hereinafter, TML-BPAF- MF) was used.

S-PEEK (0.300 g) as a polymer compound of “polymer compound obtained by introducing a proton conductive group into a polymer compound having an aromatic unit in N, N-dimethylformamide (3.240 g) as a solvent” Then, TML-BPAF-MF (0.060 g) as compound X and methanesulfonic acid (0.162 g) as acid catalyst were added to prepare a homogeneous solution. The solution was placed in a petri dish having an inner diameter of 60 mm and dried under vacuum at 150 ° C. for 5 hours. Then, after laminating in the order of SUS plate / polytetrafluoroethylene sheet / obtained film / polytetrafluoroethylene sheet / SUS plate in order from the bottom, this laminate was placed on a pressure plate heated to 150 ° C. The film was hot-pressed under the condition of 9 MPa and held for 30 minutes to obtain a cast film of Example 1.
(Example 2)
Example 1 was repeated except that dimethyl sulfoxide was used as a solvent.
(Example 3)
Example 1 was repeated except that N-methylpyrrolidone was used as a solvent.
Example 4
<Manufacture of catalyst layer transfer sheet>
The catalyst layer was prepared by the following procedure. First, as a fuel cell composition, a polymer of “polymer compound obtained by introducing a proton conductive group into a polymer compound having an aromatic unit in N, N-dimethylformamide (3.240 g) as a solvent” A uniform solution was prepared by adding S-PEEK (0.300 g) as a compound, TML-BPAF-MF (0.060 g) as a compound X, and methanesulfonic acid (0.162 g) as an acid catalyst. Next, after adding platinum-ruthenium-supported carbon catalyst powder (TEC61E54, manufactured by Tanaka Kikinzoku Kogyo Co., Ltd., 0.833 g) to pure water (0.833 g), N, N-dimethylformamide (8.330 g), Then, the polymer electrolyte solution (0.180 g) prepared above was added in order, and stirred for 30 minutes using a magnetic stirrer to obtain a fuel cell catalyst layer forming material. Subsequently, the catalyst layer forming material for a fuel cell was applied to a titanium sheet (50 μm) using a doctor blade with a gap (100 μm). Finally, the catalyst transfer sheet of Example 4 was manufactured by drying for 1 hour in a blowing oven (150 ° C.) and then for 5 hours in a vacuum oven (150 ° C.).
(Example 5)
Example 4 was repeated except that dimethyl sulfoxide was used as the solvent.
(Example 6)
The same operation as in Example 4 was performed except that N-methylpyrrolidone was used as a solvent.
(Comparative Example 1)
Example 1 was repeated except that methanesulfonic acid was not added to the solvent.
(Comparative Example 2)
Example 2 was repeated except that methanesulfonic acid was not added to the solvent.
(Comparative Example 3)
Example 3 was repeated except that methanesulfonic acid was not added to the solvent.
(Comparative Example 4)
Example 4 was repeated except that methanol was used as the solvent.

  Table 1 shows the weight loss after the cast membranes produced in Examples 1, 2, 3 and Comparative Examples 1, 2, and 3 were immersed in methanol (100 wt%) and allowed to stand in an oven at 60 ° C. for 100 hours. Is a measured value. From this result, it was found that the cast film produced in the example had less weight loss than that of the comparative example, that is, excellent in methanol solubility resistance.

表２は、実施例４、５、６、および比較例４の触媒層転写シートの形状を目視した結果である。この結果から、実施例で作製した触媒転写シートの触媒層は比較例のものと比べてヒビ割れが非常に少ない（特に本実施例ではヒビ割れがない）ことが判明した。

Table 2 shows the results of visual observation of the shapes of the catalyst layer transfer sheets of Examples 4, 5, and 6 and Comparative Example 4. From this result, it was found that the catalyst layer of the catalyst transfer sheet prepared in the example had very few cracks compared to the comparative example (particularly, in this example, there was no crack).

The membrane electrode assembly for direct methanol fuel cells according to the present invention has various industrial applicability including fuel cells represented by direct methanol fuel cells.

Claims (16)

At least a polymer compound in which a proton conductive group is introduced into a polymer compound having an aromatic unit, at least one compound X having two or more groups represented by the following general formula (1), and a solvent A fuel cell composition comprising a solvent having a boiling point of 100 ° C. or more and 300 ° C. or less, and 1 to 10 parts by weight of a polymer electrolyte with respect to 100 parts by weight of the solvent ; A composition for a fuel cell catalyst layer forming material, comprising an acid catalyst that promotes a chemical reaction with compound X.
-CH ₂ OR ··· (1)
(Wherein R represents hydrogen, an alkyl group or an acyl group, one of R contained in the compound may be the same or different to, respectively therewith each other physician.) The composition for a fuel cell catalyst layer forming material according to claim 1, wherein the solvent is N, N-dimethylformamide, dimethylsulfoxide, or N-methylpyrrolidone. The composition for a fuel cell catalyst layer forming material according to claim 1, wherein the acid catalyst is methanesulfonic acid. The composition for a fuel cell catalyst layer forming material according to any one of claims 1 to 3, wherein the proton conductive group is a sulfonic acid group. The ion exchange capacity of a polymer compound in which a proton conductive group is introduced into the polymer compound having an aromatic unit is 0.9 meq / g or more and 6 meq / g or less. 5. The composition for a fuel cell catalyst layer forming material according to any one of 4 above. The composition for a fuel cell catalyst layer forming material according to any one of claims 1 to 4, wherein the polymer compound having an aromatic unit is an aromatic polyether polymer. The fuel cell according to any one of claims 1-6 wherein at least one or more compounds X having a group represented by the general formula (1) two or more, characterized by being represented by the following structural formula Composition for catalyst layer forming material .

The catalyst layer forming material for fuel cells you comprising the catalyst for a fuel cell catalyst layer forming material composition and fuel cell according to any one of claims 1 to 7. Under Symbol (I), (II), (III) and / or comprising the step of (IV), a manufacturing method of a fuel cell catalyst layer comprising a catalyst layer-forming material for a fuel cell according to claim 8.
(I ) a step of coating the fuel cell catalyst layer forming material on a substrate;
(II) removing the solvent from the catalyst layer forming material,
(III) a step of chemically reacting the polymer electrolyte and the compound X contained in the composition for forming a fuel cell catalyst layer to obtain a reaction product;
(IV) A step of removing the acid catalyst from the catalyst layer. The method for producing a catalyst layer for a fuel cell according to claim 9, wherein the step (III) is heating at a temperature not lower than the temperature at which the chemical reaction proceeds and not higher than 300 ° C. The method for producing a fuel cell catalyst layer according to claim 9 or 10 , wherein the substrate is a polymer sheet. The method for producing a fuel cell catalyst layer according to claim 9 or 10 , wherein the substrate is an inorganic sheet. The method for producing a fuel cell catalyst layer according to claim 9 or 10 , wherein the base material is a conductive porous sheet. The claims 1 to 7, the fuel cell catalyst layer which is composed of a fuel cell catalyst layer forming material composition according to any one of are arranged on at least one surface of the polymer electrolyte membrane A membrane electrode assembly for a fuel cell. Wherein the step of removing the acid catalyst from the catalyst layer, the manufacturing method of the fuel cell catalyst layer according to any one of claims 9-13, characterized in that the contact between the catalyst layer and the water. A fuel cell comprising the membrane electrode assembly for a fuel cell according to claim 14 .